Conventional substrate supports utilized in deposition process chambers may include a heater plate fabricated from a steel alloy, for example, such as stainless steel. However, the inventors have observed that the low heat conductivity of stainless steel may create a temperature gradient across the heating plate (e.g., a temperature variation from the center to edge of the heater plate), causing uneven heating of the substrate, thereby leading to process non-uniformities. In addition, the high (radio frequency) RF resistivity of the stainless steel causes non-uniform plasma distribution, thereby further leading to non-uniform deposition of materials atop the substrate in plasma-assisted substrate processes.
The inventors have also observed that when using a substrate support having a metal heater plate during a substrate process (e.g., a deposition process), contamination of the substrate may occur as a result of metal to substrate contact. For example, when utilizing a conventional heater plate fabricated from stainless steel, iron (Fe) from the heater plate may diffuse into a back surface of the substrate, thereby contaminating the substrate.
Therefore, the inventors have provided embodiments of improved substrate supports.